The present invention relates to a plasma apparatus, and more particularly, to a resonant network for plasma power supply and a power supply device using the same.
To generate the high frequency power required by current plasma devices, a resonance type power conversion device which is easy to output a constant current is used. Although these power conversion devices generally control the output current with frequency control techniques, because of the electrical resistance of the plasma load that varies in inverse proportion to the output current in the case of a plasma load, it is impossible to control the output current by a general frequency control technique. In order to counter this, in the resonant converter for plasma load, after configuring a system using the LC resonant network of FIG. 6, the system is operated at a resonance frequency having a constant output current regardless of the electrical resistance of the load.
In addition, a plasma power conversion device including a resonant converter is recently used for semiconductor equipment and environmental purification equipment, and as its use is widespread, it requires a wide range of output current control. When the plasma power conversion device satisfies these requirements, at the same time, phase shift control is performed at the resonance frequency to avoid drop-out.
However, in order to perform the phase shift control and to control the output current in a wide area, a Zero Voltage Switching (ZVS) operating area must be considered in resonant network design. The resonant converter of the LC resonant network structure is limited in the design of an additional inductor by the plasma reactor, so that it was difficult to perform ZVS operation at low current in the design range having the output current range of the LC resonant network.
In addition, when ZVS operation is difficult, switches of a power supply may receive great stress and affect system safety.